It enables a user to find and install software unauthorized by Apple on jailbroken iPhones, iPads and iPod Touch devices.

Cydia is based on APT, ported to iOS as part of Jay Freeman's Telesphoreo project.

[5][6] Some Cydia repositories host open source packages as well as paid modifications for jailbroken devices.

[7] Many ports of existing POSIX-compliant command line tools are available on Cydia as well, including bash, coreutils and OpenSSH, meaning the device could potentially be used as a full-fledged BSD workstation, although missing some development tools.

[9] After a bug related to PayPal's digital token authorization was discovered via TechCrunch,[10] Freeman decided to shut down the Cydia Store on December 16, 2018.

Advocates offer that developer tools installed from Cydia can help add extra security.

[16] On December 15, 2010, SaurikIT filed a dispute with World Intellectual Property Organization against Cykon Technology Limited of Kowloon, Hong Kong over the rights to the domain name "Cydia.com", which was registered in 2002.

[19] On August 18, 2011,[20] SaurikIT filed a lawsuit against Hong Kong owner of Cydia.com regarding the same domain name.

[27] On February 26, 2018, CoolStar launched the initial release of Electra, giving access to Cydia from iOS versions 11.0-11.1.2.